Burglar alarm for motor vehicles



Aug. 31, 1943. M. L. JACOBS BURGLAR ALARM FOR MOTOR VEHICLES Filed May1.3, 1942 hven/ior looped upper end 8 of a contact arm 9.

Patented Aug. 31 1943 or PATENT ICE,

l 2,328,2l5 m g BUR LAB ALABM O QTOMEH Q SE Marcellus Luth'enJacobs,Minneapolis, Minn.- v I A p canpama 13, 1942. Serial-No. 442,731

action (or. zoo-52 This-inv t on e at o a a m; devi es; and more pa tcula o. a arm r mo or. ehicles andrthe k to pr en att m te unau ho iseduse thereof.

Alarm de i e v eviou b en e l ped whi hin ud a circuit make n rb calie iaving a. contact i the form o a p dulumr hi li s adapted to swingagainst another. contac hen the vehicle is set. in motionand-thecircllit; 1 1, 9? otherwise bro en by a oc con o led sw ch whichcan be operated only by the authorized user of the vehicle.

Onedrawbackof the, prior devices is that they are so constructed thatwhen the vehicle is parked on a longitudinal or lateral incline thependulum, like contact element Will complete the circuit and thus renderthe device useless. Another disadvantage in such devices is that whilesome of them are adjustable to increase or decrease the gap in thecircuit maker such adjustment has been unhandy and more or lessdifficult to attempt.

It is an object of my invention to provide an alarm device which willfunction properly or normally even though the vehicle upon which it ismounted may not be parked on a level spot, the alarm itselfautomatically compensating for the slanted position which the vehiclemight assome.

Another object of the invention is to provide an alarm device which isquickly and easily adjustable to make it more or less sensitive tovehicle movement as desired.

These and other objects and advantages of the invention will more fullyappear from the following description made in connection with theaccompanying drawing, wherein like reference characters refer to thesame parts throughout the views, and, in which:

Fig. 1 is a plan view of the alarm;

Fig. 2 is a vertical section taken on the line 2 2 of Fig. 1;

Fig. 3 is a section taken on the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary section taken on the line 4-4 of Fig. 2; and

Fig. 5 is a diagrammatic view showing a complete alarm system.

In the drawing there is shown an alarm having a casing C with a top 6thereon. An eye bolt 1 is secured to the casing top 6 and extendsdownwardly from the other side thereof to receive the The contact arm 9is suitably connected to a weight Ill. and as can readily be seen thearnr 9 isfree toswing inany direction. v p v Secured to the casing topBclosely adjacent he eye bolt 1 s an eye b l H: hav n a e tac a m I1suspended. the e m o .0 1.- ca at ve y free win n m ementecur dflo h QWQ7 l. ecfin fifthfi Conta t an. '2 is a t hich ext nds lateral yr m e. nof said ta arm 121a,. hcmcr; at iell X- n in por ion f: id; at '3. sv Prid d; W a ectan la ape u e t stimul be. no ed het.-. he or ion: o thevlate 1. ose to h ont c are I l sselidandj here e mom-hea ly weightedthan that portion of said plate I3 which has the aperture I4 formedtherein. This unequal distribution of weight in the plate I3 causes thearm I2 to hang in a vertical position when the casing C is in a rightposition.

The first mentioned contact arm 9 has a small thin plate I5 securedthereto and said plate I5 and the adjacent portion of said arm 9 lie inand extend through the aperture [4 in the laterally extending plate I3on the arm I2.

As indicated in Fig. 5 the contact arm I2 is connected by a wire I6 to asuitable ground I1. Contact arm 9 is connected by a wire I8 to theground side of a horn I9 which may conveniently be a conventional hornof a motor vehicle. The positive side of the horn I9 is connected by awire 20 to the positive side of the battery 2i and the negative pole ofsaid battery is shown connected by a wire 22 to a ground 23. An alarmsignal lamp 24 is connected in parallel by Wires 25 and 26 to wires I8and 2:] respectively. Thus when the circuit is energized any jostlingmovement of the vehicle as it is being driven or towed off will causethe laterally extending plate I3 on the arm I2 to engage the contact arm9 and energize the alarm circuit. rdinarily, a keyed controlled switchis placed in the circuit but this is conventional and is not shown sinceit has nothing to do with the present invention.

In order to increase or decrease the sensitivity of my alarm switch Imake the eye bolt 1 which supports the contact arm 9 rotatable in thecasing top 6, and the upper end of said eye bolt I is connected to asuitable pointer 21. The free end of the pointer 21 is adapted to swingalong a series of graduations 28 which indicate the position of thesmall plate I5 on the contact arm 9 relative to the sides and ends ofthe aperture I4 in the laterally extending plate I3.

Naturally, in the position of the plate I5 shownv in Fig. 4 the contactarms 9 and I2 can describe much greater relative movement than if thepointer 21 were swung 90 degrees to bring the width of the plate 15 onarm 9 transversely of the aperture 14 in the laterally extending contactmember IS. The operator of the vehicle can tell at a glance the relativepositions of the contact members and can quickly and easily set theplate [5 in a position desired by swinging of the pointer 21.

Due to the fact that the eye bolts 1 and II which support the contactarms 9 and I! respectively are positioned very close together thevehicle and alarm unit can be brought to rest on laterally slopingstreets or on hills and the 9 and 12 will swing to approximately the 7same relative positions which they have in the drawing. This is notpossible where only one of the contact arms is swingable.

The weight i 0 on the arm 9 is provided so that when the alarm device isshaken due to movement of the vehicle one arm will swing to a greaterdegree and with a diiferent timing than the other, thus insuring properestablishment of the alarm circuit.

From the foregoing description it will be seen that I have provided analarm device particularly adaptable for use on motor vehicles which issimple in construction, efficient in operation under varying conditionsand very easily adjusted to various degrees of sensitivity.

While I have shown one specific form of my invention in the drawing, itwill, of course, be understood that various changes may be -made in theform, details, arrangement and proportions of the various parts withoutdeparting from the scope of my invention.

What is claimed is:

1. In an alarm device for vehicles, a pair or relatively movable contactarms, means for supporting said arms, the first of said arms having aportion substantially encircling the second of said arms in spacedrelation thereto, said encircling portion defining an elongatedenclosure, the second or said arms having its encircled portion crosssectionaliy elongated, and one or said arms being rotatable relative tothe other to vary the spacing between said elongated enclosure of saidfirst arm and said cross sectionaliy elongated portion of said secondarm.

2. In an alarm device for vehicles, a pair of independently movablecontact arms, means for supporting said arms, the first of said armshaving a portion substantially encircling the second of said arms inspaced relation thereto, said encircling portion defining an elongatedenclosure, the second of said arms having its encircled portion crosssectionaliy elongated, one of said arms being rotatable on said supportand relative to the other or said arms to vary the spacing between saidelongated enclosure of said first arm and said cross sectionaliyelongated portion of said second arm, and means carried by said supportand connected to said rotatable arm for moving said rotatable arm tovary said spacing between said arm.

MARCELLUS LUTl- IER JACOBS.

